Method and apparatus for assembling exterior automotive vehicle body components onto an automotive vehicle body

ABSTRACT

The present invention generally relates to a method and programmable apparatus for the assembly of body components to an automotive body that has undergone a progressive series of framing and welding steps so as to produce a structurally rigid body frame, termed a body-in-white. More specifically, this invention relates to creating a new net locating scheme (X-Y and Z Cartesian coordinate system) for a body-in-white to direct associated tooling to create net attachment features on a rigid body frame with respect to a new net locating scheme so that components may be attached to an automotive body at a net location eliminating the need for any slip plane attachment techniques.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part application which claims thebenefit of nonprovisional U.S. patent Ser. No. 10/146,780 filed May 16,2002, now U.S. Pat. No. 6,691,392 B2 issued Feb. 17, 2004, which claimsthe benefit of U.S. provisional patent application Ser. No. 60/291,522filed May 16, 2001.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a method and apparatus forthe assembly of body components to an automotive body that has undergonea progressive series of positioning and welding steps so as to produce astructurally rigid body frame, termed a body-in-white. Morespecifically, this invention relates to reestablishing a new grid system(XYZ coordinate system) for a body-in-white, after assembly, so as todirect the associated tooling to establish net attachment positions forall body components thereby eliminating the B′_(L), B′_(R), C′_(L),C′_(R) need for any slip plane adjustment techniques.

2. Description of the Related Art

For many decades, automobile and truck body frames, that typicallyinclude at least an underbody, a pair of side frames, and front and rearheaders, conventionally undergo a progressive series of positioning andwelding steps before a structurally rigid body frame, termed abody-in-white, is produced. Though bodies are still manually assembledand welded, emphasis on automated assembly and welding operations hasfor many years generated numerous automated and semi-automated framingsystems.

In an attempt to create and maintain dimensional integrity in thebuilding of automotive bodies, typically, framing systems that involve adegree of automation include the operations of locating the componentsrelative to each other on the underbody. Primary locating pointsestablished on the underbody are used throughout the body shop operationas well as in the body inspection room and are generally established bylocating on each of the rails, a four way locating pin forward and a twoway locating pin rearward. Usually, the underbody is then clamped inplace at specific points of location. The primary locating points arealso used to locate for purposes of inspection in the body build shop.The components are located relative to each other and relative to theunderbody and are loosely assembled to each other. Typically, thevarious components include a floor panel, right and left body sidepanels, a dash panel and either a roof panel or transversely extendingheader members upon which a roof panel is subsequently mounted. Afterthese individual panels are stamped, in some applications, preliminaryassembly operations are performed on individual panels as, for example,adding door hinge and latch hardware to the body side panels atapproximate locations on a door opening, adding seat mounting bracketsand reinforcements to the floor panel, etc.

The set of panels that constitute a subassembly of the finished vehiclebody are then brought together and loosely assembled to each other. Thisinitial loose assembly technique is frequently accomplished by a socalled “toy tab” arrangement in which one panel is created with a tabprojecting from one edge that is received in a slot in an adjacentpanel. This technique interlocks the panels and frame members to eachother to the point where they will not separate from each other, butdoes not achieve a rigid assembly, that is, for example, the side panelsmay tilt slightly relative to the floor panel. Alternatively, someinitial pre-tack welding may be performed in order to loosely maintainthe components together. The loosely assembled subassembly is thentransported to a framing/welding station whereat, in order to accuratelyestablish the desired final geometry of all of the components of thebody-in-white, the toy tab components are clamped to locating frames,often termed gate fixtures. Thereafter, welding operations, areperformed within a framing and subsequent respot station to morepermanently and securely weld the components together and to accuratelyform a rigid structure referred to as the body-in-white. Current bodyframing stations employ both fixed and robotic welders that can beprogrammed to perform several welds at different locations on the bodyin one framing station. The welders typically are located at oppositesides of the conveying line at the welding station, and when the body'ssubassembly is located in the welding station, the fixed weldings androbotic welders perform welds on designated areas on the body. In thosecases where clamping frames are positioned on opposite sides of thebody, clearance problems may restrict motion of the welding heads thatmust pass through the clamping frame before they have access to specificareas of the body to be welded. This will result in the performance ofonly a portion of the required welding at one station and theadvancement of the partially welded subassembly to a subsequent respotwelding station where different clamping frames allow the welding headto access those portions of the body assembly that could not be reachedby the welding heads in the first station. After the body is transportedto the final welding, or respot station, the remaining welds are made toestablish a structurally rigid body frame.

Although many variations of the above process are known, it is thegeneral object of each framing system to accurately net locate the bodycomponents relative to each other and maintain the established netlocation or position throughout the later welding operations, until thestructural rigidity of the body-in-white is sufficient to preserve thedesired geometric configuration throughout the assembly process.

It is readily recognized that these conventional assembly techniquesinclude many assembly steps that require parts to be physically stackedon top of one another and then secured to each other by welding, andwherein each component is created with a certain accuracy and tolerancelimits. That is, a particular component, and any point on thatcomponent, is typically required to be manufactured to a specificdimensional configuration, within a specified tolerance range. If anindividual panel to be affixed references a point on another panel, thereference point also has a dimensional tolerance variation. Thetolerance of the assembly formed by these components will also be“stacked” together. That is, the dimensional tolerance of the firstpanel will be added, to some degree, to that of the second panel to beattached thereto. As more components are fixed to the assembly thatreferences additional attachment points, the tolerances of theindividual points are “stacked” to create a greater tolerance variationfor the “stacked” components.

The small tolerance variations in the primary locating points forlocating the underbody combined with the gate fixtures that typicallyallow some play in the positioning of the panels prior to clampinginherently results in some built-up inaccuracies for the body-in-white.Also, the repositioning of the framing system in a respot station,again, results in an additional positional tolerance variationinherently creating additional inaccuracies for the location of thevarious panels with respect to each other. Accordingly, it is quiteevident that as a number of panels with positional dimensionaltolerances are stacked the total manufacturing tolerance of the framedbody-in-white will increase. Experience has shown that the “stacking”built-in tolerances in the framing process increases the totalmanufacturing tolerance and can become quite substantial.

Accordingly, over a period of years, many have attempted to improve themanufacturing method so as to reduce the overall or total tolerance invehicle assemblies utilizing a variety of techniques in an attempt toreduce the inherent inaccuracies of the vehicle body assembly as well asthe body-in-white.

To attempt to reduce the inherent built-in inaccuracies in the processof building automobile bodies with the objective of reducing overalltolerance variations, many alternative framing schemes have beenproposed over the years. For example, DeRees, U.S. Pat. No. 5,090,105,teaches a modular vehicle construction assembly method in which variousstructural modules are fabricated and assembled with operating vehiclecomponents prior to mounting with other fabricated and assembledmodules. For example, a first module having a chassis frame and apassenger platform that is used in the formation of the underbody of thevehicle is proposed. A second module in the form of a cowl or dashboardincludes a structural frame, preferably formed from stamped panelcomponents, that include a windshield frame portion integrally formedwith a dash panel frame portion. A third modular component includes aflooring platform, two first side-wall structures and at least oneclosure device extending across the first sidewall structures above orat one end of the flooring system. The fourth module includes two secondsidewall structures, reinforcement for supporting the second sidewallstructures in a fixed position with respect to each other, a hood paneland device for displaceably mounting at least a portion of the fourthmodule to the first module. Each of the first through fourth modules iscompletely assembled, including the installation of vehicle operatingcomponents, prior to its attachment to the other modules. The resultingstructure incorporates each of the modules by locating each module at anet position thereby reducing the overall built up tolerance for thecomplete assembly. However, within each module, DeRees is stillproposing that the device for securing the panels together utilizesconventional welding techniques or welding substitutes such asmechanical interlocking of the panels, mechanical fastening, bondingwith adhesives, bolting, riveting or the like.

Angel, U.S. Pat. No. 6,378,186, teaches a framing device for assemblingand welding a body-in-white utilizing completely separate framing andwelding operations that are typically intermixed in conventional framingsystems. The framing device is a unitary frame structure within which anunderbody, side frames, and other body components can each be supportedand accurately positioned with respect to each other prior to thewelding operation. Using an appropriate number of clamping devices, thenet position of the body components that constitute the body-in-whiteare properly established and maintained, such that gate fixtures areunnecessary during the welding operation. The structure of the framingdevice provides considerable access to the body-in-white supportedwithin the interior of the framing device such that a greater number ofwelding guns can be used during the welding process to complete all ofthe welding necessary to maintain the rigidity and geometry of thebody-in-white in a single welding operation or station.

Bonnett et al., U.S. Pat. No. 5,845,387, teach a method of constructinga vehicle body with reference to a single assembly station by movingmultiple panels into an assembled position nonclampingly fixed with anadhesive and in spaced relationship without direct contact therebetween.The vehicle body is constructed by presenting a plurality of discretebody panels into assembled positions with respect to a single base forapplication of an adhesive thereon to fix the body panels in anonclamping, spaced relationship without direct contact therebetween.The body panels include an underbody, a first side panel on a first sideof the underbody and a second side panel on a second side of theunderbody, a front end member mated with the underbody, the first sidepanel and the second side panel, and a roof panel substantiallyco-planar with the underbody in mating relationship with upper matingflanges on the first and second side panels. Such structure avoidstolerance stack-up between the assembled panels by controlling theadhesive bond gap variance between the panels. The adhesive is aheavy-duty urethane structural adhesive. The resulting vehicle bodyassembly reduces tolerance stack-up and has the additional advantage ofhaving relatively little inherent stress points developed between matingpanels since they are assembled at a single stage framing fixture, orassembly apparatus.

Oatridge et al., U.S. Pat. No. 6,360,421, like DeRees, teach amanufacturing or assembly technique wherein the assembly includes aplurality of individual components that are independently formed into asubstantially rigid initial subassembly structure thereafter, for eachremaining component referencing from the substantially rigid structure adesired position for each remaining component and fixing such remainingcomponent to the subassembly at the desired position whereby the overalltolerance of the manufactured assembly is reduced.

Although a majority of the prior art has recognized the existence ofbuilt in inaccuracies in the building of automotive bodies, by thestacking of tolerances between adjacent components, resulting inunacceptable mating conditions, little has been said in the prior artregarding those inherent inaccuracies of the various processesthemselves. For example, many of the processing techniques require therigid clamping of the various components, panels or subassemblies on thefixtures for the purpose of obtaining maximum support rigidity beforethe components are welded together. However, if any misalignment existsbetween associated components or panels, the spot welding that createsthe weld will tend to displace the component or panel from the desiredassembly location to some unknown position relative to design-intent oran established X, Y and Z Cartesian coordinate systems. Accordingly,although modular construction may be suggested to avoid tolerance buildup, the clamping of the modular components into the rigid fixtures caneasily result in stretching or compression points in the vehicle bodythat may cause stress induced cracks or other deficiencies especiallyafter the weld is created. Thus, the problem with existing fixtureswhether they are framing fixtures or tooling to assemble modularcomponents is that these assemblies are assembled with internal stressesthat can cause deformities in the assembled sheet metal resulting infailures to the assemblies when in use i.e. popped welds etc. Further,after clamping these components or panels into the rigid fixtures,thousands of welds are produced resulting in additional stresses as wellas distortion due to the heat and pressure associated with the use ofwelding guns leading to the conclusion that after the body-in-white hasbeen processed in the appropriate framing and welding stations, it isimpossible to know the final location of the surfaces as well as anytargets, master holes or whatever else is attached to the panels beforethe welding operations occur. Although the objective in the framing andwelding station is to locate panels at so called “net” or design-intentlocations, the variety of unknowns due to processing through thestations causes every vehicle body and its associated surfaces to bebuilt differently. In the past this has been considered to be anacceptable body to process providing that master attachment points orpanels are within an acceptable tolerance range from net ordesign-intent location. For decades, it has been common practice in theautomobile industry to incorporate a “slip plane” in the assembly ofouter body panels to the body-in-white. The slip plane enables theappropriate outer panels to be attached and manually fit at assemblyrelative to adjacent panels. Until recently, a slip plane was necessaryin order to meet quality and fit requirements of the marketplace andcompetition, and to provide an appearance that is more pleasing and moreaerodynamic due to flushness and/or alignment of features on an outerpanel with adjacent outer surfaces of a vehicle.

Slip planes are designed in component assemblies where as a result ofmanufacturing variations of the components, as for example a door and ahinge on a vehicle, it is necessary to provide a device to enable a doorto be manually fit to the body opening at final assembly. The slip planepermits fore/aft and up/down adjustment of the hinge as necessary topermit the door to be fitted within the body opening with anequidistance gap around the door and between body openings. Slip planescan be planned to be within any coordinate or plane of an X, Y and Zcoordinate system as for example on a vehicle the fore/aft direction,cross-car direction and up/down direction that are respectivelydesignated as X, Y and Z. The appropriate plane to incorporate a slipplane is based on the specific surface feature required to be alignedwith respect to an adjacent surface feature on an adjacent outer panelof the vehicle body. The slip plane is an adjustment feature thatcompensates for the inevitable tolerance variations that differs betweenvehicles. Slip planes are generally used at the interface betweenattachment points as for example a door hinge and the major trim panelsto which the hinge is to be attached to the vehicle body. Because of thetolerance variations of the body-in-white, excessive gapping may resultbetween panels or between the door and a door opening. Further, in thecase of moving trim panels such as doors, and decklids, pinch points mayoccur as a result of variation in location of the attachment point withrespect to the opening in which the major panel is mounted. Accordingly,a slip plane, as for example in the door hinge and/or door panel, hasalways been used to provide for manual final fitting of the door withrespect to the door opening to balance out the gap between the doors andmajor trim panels, such as fenders, as well as to ensure properflushness of adjacent major outer panels.

The problem of inherent stresses and distortions as a result of theassembly process has been recognized in the prior art and severalattempts to provide more accuracy in the assembly process of a vehiclehave been made in order to solve the problem.

Earlier, it was believed that by establishing the attachment points atnet or design-intent position on the body-in-white frame structure atleast some of the inaccuracies between the panel to be attached and thebody-in-white would be eliminated. However, due to the distortions ofthe body-in-white as a result of the assembly/welding processes, it wasstill necessary to provide a slip plane in order to permanently attachthe outer body attachment panels for the purpose of obtaining propergaps and correct flushness between adjacent panels as well as alignmentof feature lines between adjacent panels. The apparatus and process bywhich a device established a datum position from an object havingdimensional variations within a known tolerance range is disclosed inU.S. Pat. No. 4,976,026 to Dacey, Jr. and is owned by the currentassignee hereof. Dacey, Jr. teaches an apparatus and method forestablishing a location in space (a datum position) utilizing an objecthaving dimensional variations in each of the X, Y and Z planes within aknown tolerance range. Upon establishing a location in space, the deviceis immobilized at the datum position and work is performed on thebody-in-white with respect to the datum position. The apparatus includesa fixed base structure for rigid mounting to a floor adjacent to anassembly line, a transfer platform movably attached to the basestructure so that the transfer platform can move in a horizontaldirection with respect to the fixed base structure, a support structureassembly attached to the transfer platform that is adapted to move in ahorizontal direction perpendicular to the direction of movement of thetransfer platform, a vertical slide assembly movably attached to thesupport structure assembly and movable therewith in a verticaldirection, fluid actuated positioning and locating members attached tothe apparatus for immobilizing the horizontal and vertical movements ofthe apparatus, as well as a plurality of probes attached to theapparatus for locating pre-established selected reference surfaces orgage points from which the datum position can be established. Theinvention further includes a work performing tool attached to theposition finding apparatus so that it can perform work on the objectwith respect to the established datum position. Since the apparatus ofDacey, Jr. relied on utilizing reference positions on the body-in-white,that resulted from imprecise and unknown locations due to the inherentstresses and distortions created during the assembly process, thepositions were continuously different although within an acceptabletolerance range on each body-in-white. The datum position establishedbased on these unknown distortions of the body-in-white created by theassembly and welding processes provided so called “design-intent”positions that varied significantly as a function of the inaccuracies ofthe vehicle frame created during assembly.

Akeel, U.S. Pat. No. 5,987,726, teaches a solution to avoid the creationof internal stresses that could cause failure of the assemblies when inuse. Akeel, teaches an apparatus for positioning an object during anassembly operation including a parallel link programmable positioningmechanism having a base plate, a spaced apart locator plate and sixlinear actuator links extending between the two plates and attachedthereto by universal joints. The base plate is connected to the locatorplate with the plurality of linear actuators, each having a lower endpivotably attached to the base plate and an upper end pivotably attachedto the locator plate. When an object is mounted on the locator plate,the linear actuators are controlled to move the locator plate to apredetermined position relative to the base plate for contacting theobject mounted on the locator plate with a component to be assembled. Afeedback signal is generated representing a force supplied to thelocator plate when the object contacts the component and thereafter thelinear actuators are actuated to change the applied force in response tothe feedback signal. This locating method provides for a stress freeassembly of sheet metal components on assembly fixtures.

Kotake et al., U.S. Pat. No. 5,150,506, also teach a method ofassembling exterior parts of an automobile wherein assembly accuracyerrors of the vehicle body or body-in-white are determined by measuringthe actual positions of a plurality of reference points of thebody-in-white after it has been processed through the framing/weldingstation. Correction data is then generated by comparing the actualmeasured position of a point to the wire frame data or design-intentposition of the same point while maintaining a correlated relationshipamongst the parts, to eliminate correlated misalignment among thoseparts due to assembly accuracy errors of the body. The measurement ofthe assembled position of the vehicle body may be made at the assemblystation of the parts or at any arbitrary station that is located on anupstream side of the assembly station. In the latter case, the measuredas assembled, data is read by a processor that generates correction datafor the parts assembled positions that is transmitted from the measuringstation to the assembling station. When the vehicle body is conveyedinto the assembling station, the conveyed position is detected byencoders and the parts are assembled after corrections are made inaccordance with the correction data. The reference points of the vehiclebody are detected by the encoder device provided at the assemblingstation and, on the basis of the positional information, correction datafor each assembling position of an exterior part is calculated bycomparing the actual position detected by the encoders with the wireframe data in a computer so that the correction data is transmitted to arobot controller of a corresponding assembly robot to correct theassembling position of each part.

Accordingly, as desired, the location of any individual point on a panelafter the body has been welded together is determined by the use ofencoders and the deviation from the mean position of the point iscalculated by comparing the actual reading to the net location of wherethat point should be so that a deviation from mean of the location ofthe point is determined. This deviation, in the form of a correctiondata, is communicated to the assembling robot in order to instruct therobot of the actual position of the point on the body-in-white panelwith respect to the design-intent position so that each component to beassembled at that point may be separately adjusted to a correctedposition in order to provide a corrected attachment point for assemblingeach of the outer body panels to the appropriate holes formed in theunderbody and thereby maintain flushness of adjacent panels.Accordingly, each attachment point is selectively investigated as todeviation from mean and a correction is made when comparing the actuallocation of the attachment point to the mean location to ensure that theholes in the outer panels line up properly with the holes in theunderbody to enable a successful attachment of the outer panel andensure flushness to adjacent panels. Obviously, when using thissophisticated equipment in a production environment many problems cansurface including but not limited to, environmental debris as a resultof welding operations, sensitivity problems with the equipment,technical support team necessary to monitor equipment, etc. Also anadditional station is needed in the production line to enablemeasurement by the encoders of the actual points on the body-in-white.

Therefore, what is needed is an apparatus and technique for assemblingautomotive frame components that recognizes and accepts the existence ofthese internal stresses and distortions of the various panelsconstituting the body-in-white that have been welded with, in somecases, as many as three thousand welds, yet is able to establish areliable assembly technique utilizing a feature of Dacey, Jr., that is,insuring the fabrication of attachment points that are in a net or bestfit position on the complete body-in-white that is also then assured tobe in a known position so that the outer panels may be directly attachedto the body-in-white with attachment points assured to be in the sameposition so that the outer panels may be directly attached to thebody-in-white without the need for slip planes and without the need forbeing concerned of the inherent variations established by the bodybuilding process itself.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, there is provided a method andapparatus for optically establishing a new master locating scheme for anautomotive vehicle body, otherwise known as a body-in-white, andthereafter using robotically driven tools to precisely assemblecomponents to the body-in-white relative to its new master locatingscheme. After the body-in-white has been processed through theframing/welding station(s), work performing tools are roboticallypositioned with respect to the new master locating scheme and work isperformed on the body-in-white to create net or best-fit attachmentfeatures adapted to accommodate the attachment of other components andthereby produce a finished vehicle body that meets the flushness and gapspecifications between adjacent panels established by the vehicle designteam.

The apparatus of the present invention is intended to be part of theproduction assembly line after the various panels have been framed andwelded together as a unit to establish a completed body-in-white. Thebody-in-white is transported by a carrier device along the assemblyline, and is provided with a predetermined arrangement of datumstypically including reference holes, slots and/or surfaces. Theapparatus includes two and three-dimensional optical sensors, such asthose commercially available from Perceptron, Inc., positioned on eachside of the assembly line relative to a predetermined datum feature ofthe body-in-white. Each optical sensor is adapted for locating up/down,fore/aft and cross-car datum features of the body-in-white, and forcommunicating such location to a microprocessor. As the optical sensorslocate features that have surfaces which have been processed through theframing/welding station. The effect of distortion of these features onsurfaces and other inherent process variables of the body-in-white, as aresult of the assembly and welding processes, will be realized by thesesensors.

The microprocessor establishes specific points in terms of the CartesianX, Y and Z coordinate system that represent the primary locating pointsof the body-in-white as built, that is, including the inherent tolerancevariations and distortions caused by the framing and welding operations.The microprocessor then compares the primary locating points of thebody-in-white as built with the design-intent primary locating pointsand divides the total variable in half to generate new X, Y and Zcenterlines that takes into account the variations and distortion of thebody-in-white in the as built condition as will be discussed in moredetail hereinafter. The present invention is adapted to create separateX, Y and Z centerlines or gridlines for the body-in-white attachmentlocations as required for a particular application. For example, theoptical sensors may be configured to locate a first group of referencedatums near the front of the body-in-white to create a first specificset of X, Y and Z coordinate centerlines for the attachment of the hood,and a second group of reference datums near the rear of thebody-in-white to create a second specific set of X, Y and Z coordinatecenterlines for the attachment of the trunk.

The new X, Y and Z coordinate centerlines of the body-in-white as builtare then communicated to the robotically positioned work performingtools that perform work relative thereto. As a result of being able tobalance out any created or inherent errors of the body-in-white due toprocessing through the framing station, all attachment holes, slots,pads etc. created by the work performing tools can be located withrespect to the newly established X, Y and Z coordinate system andtherefore all locations of the attachment features are net to the newlycreated X, Y and Z coordinate system. Furthermore, the new masteringscheme creates the absolute best-fit attachment feature and completelyeliminates the need to provide for a slip plane in order to attach acomponent to the body-in-white. Therefore, any outer body component,i.e. hood, fender, doors, decklid, liftgate, front bumper, rear or frontfascia etc. being attached to the body-in-white can be fabricated withattachment feature at net or design-intent positions since they will beattached to a net attachment point on the body-in-white.

The invention also encompasses a method for establishing a new CartesianX, Y and Z coordinate system taking into account the inherent errorcreated by assembling the various panels of a vehicle body in a framingand/or welding station.

The method of establishing a new coordinate system taking into accountthe variations of the as built vehicle body upon which work is to beperformed is set forth. The method also encompasses the performance ofwork on the vehicle body at a location remote from a plurality ofindependently established primary locating points.

The principle object of the present invention is to provide a new andimproved apparatus and method for establishing a new Cartesian X, Y andZ coordinate system for a vehicle body otherwise known as abody-in-white. The invention encompasses performing work at this new X,Y and Z coordinate or grid system so as to provide net referenceattachment features for the various components that will subsequently beattached to the body-in-white.

Another object of the present invention is to provide a new and improvedapparatus and method of balancing out the inherent error generated bythe processing of the body-in-white through the framing and weldingoperations.

A further object of the present invention is to perform work on abody-in-white relative to a newly established X, Y and Z coordinatesystem so as to provide new net attachment features for the variousouter body panels and/or attachments to be made to the body-in-white.

Still another object of the present invention is to provide an apparatusthat can interact with a body-in-white and generate a new referenceposition with respect to known design-intent reference positions,balance out any errors at this given reference position and establish anew reference coordinate system for the body-in-white so that,thereafter, work can be performed on the vehicle body at a locationremote from the established reference position.

Another object of the present invention is to provide an apparatus thatrelies primarily on a programmable robotic device and associatedmicroprocessor system for accomplishing part of its motion relative toan adjacent workpiece.

Also, another object of the present invention is to provide an apparatusthat has freedom of movement in at least three dimensions to locate andlock on primary locating points of unknown dimensions and thereafterre-establish a new net X, Y and Z coordinate system for the primarylocating points that are used, in turn, by the associated tooling toperform work relative to the new net X, Y and Z coordinates on thevehicle body to create attachment features for outer panel componentsthereafter intended to be attached to the body-in-white.

Another object of the present invention is to provide a method for themanufacturer of attachment features on a vehicle body-in-white structurethat are created with reference to a newly established X, Y and Zcoordinate system based on balancing out the inherent errors existing inthe body-in-white from the framing and welding operations.

Yet another object of the present invention is to provide a programmableapparatus that has attached thereto a work performing tool net locatedto a newly established X, Y and Z coordinate system for the objectwhereafter the tool is located and held by the programmable apparatusfor a time interval sufficient to permit the tool to accomplish its taskand be withdrawn from the proximity of the object being worked on.

Yet another object of the present invention is to establish attachmentreferences on a body-in-white without the use of slip planes.

Still a further object of the present invention is to provide aprogrammable apparatus for reforming an element of an automotive innerbody panel to present a portion of the surface of such element at apredetermined net position with respect to a newly generated X, Y and Zcoordinate system for the attachment of an outer body panel thereto.

It is a further object of the present invention to provide aprogrammable apparatus and method for establishing a new X, Y and Zcoordinate system of an automotive inner body panel to present a portionof the surface of such element at a predetermined position for theattachment of another element thereto by a robot and for forming a nethole in such surface to facilitate the attachment of the elementthereto.

For a further understanding of the present invention and the objectsthereof, attention is directed to the drawings and the following briefdescriptions thereof, to the description of the preferred embodiment ofthe invention and to the claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a top view of a partial body-in-white located in the preferredembodiment master locating station with a gantry and wherein the toolinghas been removed in order to clearly view the position detectingapparatuses, the front two of which are engaged with the vehicle body;

FIG. 2 is a partial isometric view of the position detecting apparatuslocated in the front right hand primary locating points of the vehicleshown in circle 2 of FIG. 3;

FIG. 3 is an isometric view of the master locating station with theright side position detecting apparatuses located on the right sideprimary locating points and the left hand position detecting apparatusesand all associated tooling removed;

FIG. 4 is a schematic representation of the top view of the frontprimary locating points misaligned from design-intent due to theinfluences of the work performed on the body-in-white in theframing/welding station;

FIG. 5 is a schematic representation of a misalignment of the frontprimary locating points as viewed from the rear of the vehicle body soas to show the misalignment in the up/down direction of the primarylocating points;

FIG. 6 is a top view of the master locating station with a portion ofthe front gantry cut away to better illustrate the attachment of thebalancing lever and crank mechanism to the underside of the gantryspanning the production line;

FIG. 7 is a partial view of the gantry spanning the production line,having the level and bell crank system attached to the bearing and slidemechanism that is secured to the underside of the gantry;

FIG. 8 is a front end view of the master locating station with the rightside front position detecting apparatus, probes, and contact blocklocked in place and the associated locator pin inserted in the overheadsocket to establish the location of a new X, Y, and Z coordinates forthe primary locating points of the vehicle body;

FIG. 9 is a detailed view of only the input socket arrangement attachedto the end of a lever of the bell crank system with the locator pin inthe bottomed-out position as shown in circle 11 of FIG. 8;

FIG. 10 is a partial view of the master locating station highlightingthe lever and bell crank centering arrangement, having an input andoutput socket attached thereto with the respective locator pin alignedwith a first position detecting apparatus and additional locator pinaligned with a second position detecting apparatus;

FIG. 11 is a detailed view in the fore/aft direction from the front ofthe vehicle body of both input and output sockets with locator pinsbottomed-out as shown in circle 11 of FIG. 8;

FIG. 12 is a partial view in the cross-car direction of the bearing andslide mechanism and associated input socket attached to a positiondetection apparatus and output socket attached to another positiondetecting apparatus directly attached to the tools, which perform workon the vehicle body;

FIG. 13 is a top view of a partial body-in-white located in aworkstation showing electro-optical position detecting apparatuses,which are engaging with the vehicle body;

FIG. 14 is a block diagram of associated electronics of the workstationof FIG. 13;

FIG. 15 is a schematic representation of the top view of the primarylocating points misaligned from design-intent due to the influences ofthe work performed on the body-in-white in a framing/welding station andthe new grid established as a result of averaging out the totaldeviation from design-intent of the actual location of the primary asbuilt locating points; and

FIG. 16 is a schematic representation of a misalignment of the primarylocating points as viewed from the front of the vehicle body so as toshow the misalignment in the up/down direction of the primary locatingpoints and the establishment of a new grid centerline at one-half thetotal deviation of the as built location as compared to design-intentlocation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Generally shown in the Figures, is a method and apparatus for utilizingposition detection apparatuses to locate primary locating points on avehicle body, also known as a body-in-white. In accordance with thepresent invention, after the primary locating points have been locatedand the position detecting apparatus have been locked in place, a set oflocator pins and input sockets, one of which is attached to the positiondetecting apparatus and the other of which is attached to a balancinglever mechanism fixed to the gantry spanning the production line, isused to balance out or average the deviation of the primary locatingpoints in cross-car, fore/aft and up/down directions of the actualbody-in-white as built, from design-intent positions. This average orbalancing out would obviously not be required if the processing of thebody-in-white resulted in all panels and attachment points beingactually located at design-intent position after the vehicle body wasprocessed through the framing and welding station. Unfortunately, aperfect body-in-white exists only in sophisticated CAD systems on acomputer. In the real world, bodies-in-white are made with a variety ofassembled parts, each having tolerance variations resulting in tolerancestack-ups. Further, the effect of as many as three thousand (3000) weldsmake it impossible to predict the final assembled location of any pointon the body-in-white with any great specificity. Accordingly, tolerancevariations of any point on the body-in-white after processing areexpected, and acceptable within a given tolerance range. The inventioncontemplates balancing out these unknown variations and therefrom createa new known X, Y and Z coordinate system or grid for the body-in-whitein the “as built” condition. A second set of output sockets and locatorpins, one of which is mounted to the balancing mechanism, the otherbeing mounted to a second position detecting apparatus associated withthe tooling surrounding the body-in-white, interact or plug into eachother to float the tooling station into a net position with respect tothe newly created coordinate system, created by the balancing technique,so that work may be performed on the body-in-white relative to a new netX, Y, and Z coordinate system of the body-in-white.

In the context of the following detailed description of the preferredembodiment, which is a vehicle body for an automobile, reference to thefore/aft (X), cross/car (Y), and up/down (Z) axis, as well as therelative terms front, rear, top and bottom, apply to a vehicle body asviewed in the final assembled position unless otherwise specified. Also,reference to a “Class A” surface means any surface on the completelyassembled automotive vehicle body that is visible to an observer.

With reference now in detail to the Figures, FIG. 1 shows a portion of avehicle body or body-in-white A in a master locating station 10 having afront gantry 12 and rear gantry (not shown) with appropriate positiondetecting apparatuses 20 located selectively at four feature points orprimary locating points (not shown) on the body-in-white A so as to findthe actual location of unknown primary locating points on thebody-in-white A and thereafter immobilize the position detectingapparatuses 20 with respect to the primary locating points of thebody-in-white A. It is understood that the primary locating pointsselected can change based on the requirements of the specific vehicle aswell as what subjectively may be determined by the body building team tobe important features that need to be properly fit for gapping orflushness, or relative importance, as a feature line across the completebody side of the vehicle body.

The position detecting apparatus 20 selected is described in detail inDacey Jr., U.S. Pat. No. 4,813,125 owned by the assignee hereof and thatis incorporated herein by reference in its entirety. For the purpose ofclearly understanding the current invention, some limited description ofthe position detecting apparatus 20 is provided. The apparatus asdescribed in U.S. Pat. No. 4,813,125 includes a fixed base structure forrigid mounting to a floor adjacent to an assembly line, a transferplatform is movably attached to the base structure so that the transferplatform can move in a horizontal direction with respect to the fixedbase structure. A support structure assembly in the form of an angleplate is mounted to the transfer platform that in turn is adapted tomove in a horizontal direction perpendicular to the direction ofmovement of the transfer platform. A vertical slide assembly is movablymounted to the angle plate of the support structure and movable withrespect thereto in a vertical direction. Fluid actuated positioning andlocating members are attached to the apparatus to permit limitedmovement with respect to all three directions, that is X, Y and Zdirections and further includes a device for immobilizing the horizontaland vertical movements of the apparatus. A plurality of probes and/orcontact blocks are attached to the position detecting apparatus 20 forlocating selected pre-established reference surfaces or primary locatingpoints on the vehicle body so that the position detecting apparatus 20can move into position at the primary locating points in order to “find”the location of these points in an X, Y and Z coordinate system within aknown tolerance range. Although the position detecting apparatus 20selected is a mechanical device, it is within the scope of the inventionthat vision systems, electro-optical or other suitable sensors, orlasers in combination with robotic tools may be used to detect theposition of selected primary locating points on a body-in-white A.

As shown in FIG. 1, the position detecting apparatuses 20 are located oneach side of an assembly line spaced with respect to the body-in-white Athat will be processed therethrough. For purposes of clarity the reargantry spanning across the production line and all of the associatedtooling are not shown and further, the complete body-in-white A is notshown so as to enable viewing the position detecting apparatuses 20 inthe front and the rear of the master locating station 10. FIG. 2 is aclose up of the right front quarter of the vehicle body A beingprocesses wherein the position detecting apparatus 20 has been isolatedand illustrates a probe 22 located in a gage hole in the front pillar,defining a the actual location of point B, to establish X and Zpositions as well as a contact block 24 touching the vehicle in order toestablish a cross-car or Y position of a Class A surface C on the frontpillar.

The contact block 24 is adapted to carry a low DC voltage so as toelectrically sense contact with the pillar surface to avoid creating anexternal force on the vehicle body A that could influence the positionor location of the Class A surface. The position detecting apparatus 20moves into position against the body-in-white A to establish a cross-carlocation Y by touching the contact block 24, and a fore/aft X andup/down Z location by locating in the gage hole B. After each of theposition detecting apparatuses 20 as shown in FIG. 1 have moved intoplace by finding their respective primary locating point on the vehicle,the position detecting apparatuses 20 are immobilized according to theteachings of Dacey, Jr. To a person skilled in the art it should beobvious that in order to establish the immobilized position of all fourposition detecting apparatuses 20, the vehicle body A must come to acomplete stop position in the master locating station 10. Thebody-in-white A enters the master locating station 10 located on thesame primary locating points as established in the framing system. Theseprimary locating points are the same points used to locate the bodythroughout the body shop operations as well as in the body inspectionroom and generally includes locating on each of the rails, a four waylocating pin forward and a two way locating pin rearward. Thebody-in-white A is then clamped in place and remains at the clampedposition throughout the master locating stop station and subsequentassembly stations.

For the purpose of clarity, and with reference to FIG. 3, there is showna master locating station 10 with the appropriate gantries in the front12 and rear 14 of the vehicle body A that straddle the production lineas well as the position detecting apparatuses 20 used to locate on theright hand side of the vehicle body A. The remaining position detectingapparatuses 20 are not shown for the purpose of clarity. However, it isunderstood that the following discussion of the operation concerning theright front quarter position detecting apparatus 20 equally applies toeach of the position detecting apparatus 20 in the creation of a new X,Y and Z coordinate or grid system based on the vehicle body A as builtwith the aforementioned variations, distortions and inherent processingerrors. The work performing tools are also not shown in FIG. 3.

FIG. 3 represents a master locating station 10 that includes a frontgantry 12 at the front of the body wherefrom is suspended a lever andcrank centering mechanism 30 that can move fore/aft (X) and cross-car(Y) on a slide assembly 50 utilizing a plurality of bearings and ways inorder to be moved in the fore/aft X and cross-car Y directions for apurpose hereinafter described. As shown in FIGS. 2 and 3, the positiondetecting apparatus 20 has been moved in place by the insertion of theprobe 22 into a primary locating point or gage hole B in the vehiclebody A pillar as well as by a contact block 24 creating contact with thevehicle body A Class A surface C so as to find and locate the exactposition of the selected primary locating point for the front quarterpanel of the vehicle body A. The position detecting apparatus 20 hasbeen immobilized and is locked in this position. Since all positiondetecting apparatuses 20 operate simultaneously in order to establishthe location of all of the primary locating points on a vehicle body A,once immobilized, all four position detecting apparatuses 20 are nowpositioned with respect to selected primary locating features on theprocessed body-in-white A. As recognized by any person skilled in theart, the primary locating points will vary between vehicle platforms anddue to the distortions and stack up tolerances created in the framingand welding station, the position of the Class A surfaces C will alsovary from body assembly to body assembly and even from side to side ofthe same vehicle body A, as will be illustrated hereinafter.

For the purpose of illustrating the invention, and with reference toFIG. 4, once the position detecting apparatuses 20 are immobilized, therepresentation conceptually in FIG. 4, as viewed from the top of thevehicle body A A, reflects the position of the right hand positiondetecting apparatus 20 as shown in FIG. 3 located at the primarylocating point B, C in a direction fore/aft X further rearward from theposition detecting apparatus 20 located on the left hand side of thevehicle body A A. From this, it can easily be concluded that thebody-in-white A, as a result of distortions by processing through theframing station has moved. As a the gage hole B and associated cross-carcenterline B–B G between the two primary locating points B, B has movedrearward from the cross-car design-intent centerline D while the gagehole B and associated centerline B–B G on the left hand side has movedforward from the cross-car design-intent position D. Also, in thecross-car direction Y, the contact blocks 24 from left to right handside have detected a shift in the class A surface of C the pillar sincethe right hand side class A surface C of the pillar is further inboardfrom design-intent D while the left hand Class A pillar surface C isfurther outboard from its design-intent position as reflected by thecross-car design-intent centerline D. Similarly, FIG. 5 represents aconceptual view of the two front position detection apparatuses 20located in the master gage hole B, as viewed from the rear of thevehicle body A. The centerline B₁ C, of the gage hole or primarylocating point B on the left hand side is substantially lower than thecenterline B₂ C, of the gage hole B on the right hand side of thevehicle body A. The obvious reason for this is the fact that thebody-in-white A, as processed through the framing and welding station,has inherent variations and distortions in the various panels in whichthese primary locating points B are located and accordingly, theseprimary locating points B are not at design-intent position D nor in anyway representative of the X, Y, and Z planes or grid lines about whichthe design-intent vehicle body A is designed. It is clear that thebody-in-white A, due to its processing, has somehow been skewed in theFIG. 4 and FIG. 5 schematic representations. Any outer panel thatreferences these primary locating points B, B as currently depicted inFIG. 4 and FIG. 5 will naturally require fit and spacing adjustments toadjacent body panels and this clearly shows why in the past, a slipplane had to be used in order to allow adjustment of these panelsbecause of the unknown variations of the primary locating points B, Bfor attachments to or referencing of the outer body panels.

The invention contemplates adjusting the tooling with respect toadjusted averaged newly established X, Y and Z reference planes createdby averaging out the distance d between right B and left B primarylocating point as viewed in FIG. 4 or FIG. 5 so that the tooling canutilize this new adjusted average X, Y and Z grid positions to establisha new net reference location and perform work with respect thereto. Thenet effect of this averaging results in reducing total deviation errorfrom design-intent D to one-half, as well as to establish an actual netlocation of the “as built” body-in-white A and utilize the newlyestablished X, Y and Z coordinates as a new grid system from which toreference the tooling so that new net attachment points can be providedon the body-in-white A enabling the attachment of components to thevehicle body A at the new net attachment point without the need foroversized holes or a slip plane.

The new net locating X, Y, and Z coordinate system is establishedthrough the use of a lever and crank mechanism (or bell crank) 30 thatis attached to each gantry 12, 14 for respective fore/aft and cross-carY final positioning of attachment points. With reference to FIGS. 6 and7, there is shown the lever and bell crank system 30 encompassing acrank arm 34 located at the exact design-intent centerline D of thevehicle body A to be processed with attached input sockets 40 located atthe end of each lever 32 having one end attached to the input socket 40and the opposite end attached to the crank arm 34. The lever and cranksystem 30 is biased in the clockwise direction so that the cross-cardimension between input sockets 40 is less than the design-intentdimension, by an amount corresponding to the acceptable total deviationrange so as to always insure that the input socket 40 is within range ofa locating pin to be moved into it, as hereinafter described.

Referring to FIG. 7, the first set of input sockets 40, are mounted on abearing and a slide assembly 50 that is movable in the fore/aftdirection 52 as well as cross-car direction 54 of the complete lever andcrank system 30. The position detecting apparatus 20, shown in FIG. 8,communicates with the bell crank centering system 30 through the use ofa locating pin 62 and cylinder 60 arrangement securely fixed to anopposite end of the position detecting apparatus 20. The locating pin 62can extend from the cylinder 60 in an upward direction. As the locatingpin 62 extends toward and into the input socket 40, a set of rollers 74(shown in detail in FIG. 9) mounted 90° with respect to each other forma pocket to receive a bull nose of the locating pin 62 that continues totravel within the input socket 40 until it bottoms out. Any effect of amisalignment between flats 64 on the locating pin and the input socket40 generates a force on the lever and bell crank system 30 therebycreating rotation of the bell crank and lever system 30 and, at the sametime, the rotation forces movement of the slides along the bearings ofthe slide assembly 50 in the fore/aft 52 and cross-car 54 direction.Through the lever and bell crank mechanism 30, a balancing occursbetween the two front input sockets 40 mounted on either side of thebody-in-white A. Similar balancing occurs between the two rear sockets(not shown). The total amount of movement is a function of the totaldeviation from design-intent from which each of the primary locatingpoints B have been moved to as shown in FIG. 4 and 5 due to theframing/welding station processing.

As shown in FIG. 4 and 5, the adjustment will be balanced between rightand left sides because of the input socket 40 and locator pin 62interaction and by this balancing action, the bell crank system 30 andslide mechanism 50 will balance out at a new net cross-car position andin effect create a new centerline N₂ in the fore and aft, or Xdirection, based on actual vehicle body A built conditions. Further, asecond set of rollers 74 (not shown) within the input socket 40 also areinfluenced by the interaction of the locating pin 62 to create movementof the bearing and slide system 50 in the cross-car direction 54 tobalance out at a new cross-car position and create a new cross-carcenterline N₁ that is a net centerline for the actual vehicle body A asbuilt in the cross-car or Y direction. A third movement of additionallocator pins 62 inserted into associated input sockets 40 and relatedmovement of the slide system 50 to which the bell crank system 30 isattached is simultaneous in both the front and rear of the vehicle bodyA A (not shown). Accordingly, when both locating pins 62 are fullyinserted into the first set of input sockets 40, a new centerline forthe body-in-white A, in the “as built” position, is created in the X andY directions. A similar locating pin 62 and input socket 40 arrangement(not shown) is provided in the up/down or Z direction of the vehiclewith a similar crank and lever mechanism 30 to accomplish a similarbalancing affect (not shown) so that a new centerline N₃ or net locatingline for the Z direction is established as illustrated in FIG. 5. Uponcomplete insertion of the locating pins 62, in their respective inputsockets 40, a limit switch detects the presence of the pin 62 andsecurely locks the pins 62 in place in the first input sockets 40.

Now that the variation of the inherent errors of the processing of thebody-in-white A has been balanced out or averaged across a new set of X,Y and Z centerlines, as discussed above, and the locator pins 62 havebottomed out in their respective input sockets 40 the work performingtools (not shown) can be brought into place to perform work on thebody-in-white A. This is accomplished by providing an additional set ofsockets 70, commonly referred to as, output sockets as shown in FIGS.8–12.

An additional set of output sockets 70 are physically attached to thesame slide and bearing assembly 50 mounting plate as the first set ofinput sockets 40 attached to the bell crank and lever system 30. Anadditional or second position detecting apparatus 80, directly attachedto all of the tools that surround the body-in-white A, is spacedrelative to the first position detection apparatus 20. Accordingly, asthe additional position detecting apparatus 80 floats to permit completeinsertion of a locator pin 72 in the output socket 70 the tooling willrelocate itself with respect to the new X, Y and Z gridlines for thevehicle body A as built. This second set of sockets 70 receives thelocator pins 72, of additional position detecting apparatus 80 locatedadjacent to the immobilized position detecting apparatus 20. Since theoutput sockets 70 are fixed to the bearing and slide structure 50 as thelocator pins 72 are located or floated into the fixed output sockets 70,the additional position detecting apparatus 80 floats in all 3directional planes X, Y, and Z to allow the pins 72 to completelyposition themselves and bottom out in the sockets 70.

As the second position detecting apparatus 80 floats into place thecomplete tooling system directly or indirectly attached to the secondposition detecting apparatus 80 will also float so as to position itselfnet with respect to X, Y and Z coordinates and relative to the newcenterlines N₁, N₂, N₃, based on the actual built condition of thebody-in-white A. When the locator pins 72 bottom out in the outputsockets 70, a signal is generated and communicated to the secondposition detecting apparatus 80 so as to immobilize this apparatus inthis position thereby establishing a net location for all workperforming tools relative to the new net coordinate system, that is, X,Y and Z that reflects the actual vehicle body A as built wherein thetotal variations and distortions of the selected primary locating pointsB have been averaged out to set a new net position from which tools canperform work on the body-in-white A.

The work to be performed on the body-in-white A and the sequence inwhich to perform the work can vary. Generally, a person skilled in theart will recognize that the speed at which this work is accomplished isa direct function of the access that is created for each of the workperforming devices. The majority of the work concerns piercing holes forattachment of outer body panels such as doors, decklid, liftgate,bumpers, facia, hood, and fenders. However, it is also contemplated thatattachment features can be established for head lamps, shock towers,tail lamps, fuel filler, instrument panel, seats, consoles and the like.All of the work performing tools operate under principles that need notbe described herein.

While the method and apparatus of the invention has been described byway of illustration involving 4 position detecting apparatuses 20 inconjunction with two lever and crank centering systems 30 to balance outand establish a new X, Y and Z reference coordinate system for abody-in-white A, it is within the purview of the present invention toestablish and immobilize any two or more position detecting apparatuses20 and an associated lever and crank balancing or averaging mechanism,thus, creating a new X, Y and Z grid system or reference planes fromwhich useful work can be performed.

As stated previously above, it is within the scope of the presentinvention that the position detecting apparatus 20 can also take theform of an optical sensor such as a laser. Accordingly, FIG. 13illustrates a plan view of an alternative embodiment of the presentinvention that represents an electro-optical analog to the mechanicalembodiment described previously with reference to FIGS. 1 through 12.Whereas, the previously described embodiment mechanically re-establisheda coordinate system for an as-built vehicle body A, this embodiment,using a microprocessor, electro-optically re-establishes a coordinatesystem for an as-built vehicle body A so that work can be performed bytooling directed by programmable robots.

FIG. 13 generally illustrates a workstation 110 for processing abody-in-white, or vehicle body A A. The workstation 110 is ultimatelydirected to forming net-located attachment features programmed bycomparing as built positions with design-intent positions andestablishing a new net or best fit attachment feature on the vehiclebody A A, regardless of the as built location of the vehicle body A A.In other words, the objective of the workstation 110 is to net-locatesuch attachment features with respect to a newly established net gridsystem relative to design-intent vehicle body coordinates, regardless ofthe position, location, or orientation of the body-in-white coordinatesafter the effects of the framing/welding operation. The presentinvention is particularly effective if the actual vehicle body Acoordinates of actual or target locating features B′_(L), B′_(R),C′_(L), C′_(R) (see FIGS. 15 and 16) are within tolerance. If, however,the target locating features B′_(L), B′_(R), C′_(L), C′_(R) are notwithin their predetermined tolerance band coming into the workstation110, then the present invention is not designed to correct for suchout-of-tolerance conditions and the vehicle body A may need to berejected and repaired. As defined herein, the terminology—targetlocating feature—is equivalent to the terminology primary or actuallocating feature. Also as defined herein, an attachment feature can bean attachment point, surface, position and the like. Likewise, a targetlocating feature can be a locating point, surface, position, and thelike.

The workstation 110 is just one station of a much larger vehicleassembly line. The vehicle body A A may arrive at the workstation 110 inany manner including on a sled, conveyor 112, or the like. Preferably,once the vehicle body A A occupies a desired position within theworkstation 110, locator pins 114 engage preformed setup locatingfeatures (not shown) on the vehicle body A such as on an underside ofthe vehicle body A A near the four corners thereof, as is well-known inthe art. Two-way and four-way locator pins (not shown) could also beused as described above with respect to the mechanical embodiment. Thelocator pins 114 are permitted to float to a certain extent toaccommodate dimensional variations in the predefined locating points onthe vehicle body A.

The workstation 110 also includes several position detecting apparatuses116 that are interfaced to a common machine vision controller 118 asshown in FIG. 14. A pair of up/down position detecting apparatuses 116are mounted to an overhead frame 120, under which the vehicle body A Ais stationed. An additional pair of cross-car and fore/aft positiondetecting apparatuses 116 are mounted to opposed floor stanchions 122,between which the vehicle body A is stationed. The position detectingapparatuses 116 are preferably PERCEPTRON robot guidance sensors, whichare well-known in the art and are exemplified in U.S. Pat. No.4,645,348, which is incorporated by reference herein. In brief, eachposition detecting apparatus 116 includes a light source, such as alaser diode, that is modified to generate a structured light pattern forilluminating target locating features on a target object. The structuredlight pattern is preferably projected onto the target locating featuresat an angle that is normal to the target feature. As defined herein, alocating feature is equivalent to a locating point or surface. A sensordevice within the position detecting apparatus 116 receives a reflectedlight image through a set of sensor optics, such as photo-diodes, whichtransduce the reflected light image into electrical signals whose signalvalues are approximately proportional to the intensity of the incominglight. Each position detecting apparatus 116 is calibrated in referenceto known X, Y, and Z Cartesian coordinate hardpoints within theworkstation, such as the vehicle body A locator pins 114. Calibrationand setup methods are well known in the art and are exemplified by U.S.Pat. No. 4,841,460, which is incorporated by reference herein. Also,calibration and setup procedures may be carried out using AUTOCAL orDYNACAL, available from Dynalog, Inc. of Bloomfield Hills, Mich.

Referring now to FIG. 14, there is provided an illustration of oneembodiment of the present invention in block diagram form. The positiondetecting apparatuses 116 are all coupled to the machine visioncontroller 118, which processes electro-optical signals from theposition detecting apparatuses 116. The machine vision controller 118compares the received electro-optical signals to calibration referencedata to yield actual X, Y, and Z Cartesian coordinate data that arerepresentative of the actual as built location of the target locatingfeatures.

The machine vision controller 118 is also coupled to a central processor124, which executes a predefined best-fit algorithm on the coordinatedata from the machine vision controller 118. It is contemplated that thecentral processor 124 could be incorporated within the machine visioncontroller 118 and need not be a separate device. In any case, thecentral processor 124 includes a controller 126, memory 128, andinterface electronics 130. The interface electronics 130 may conform toprotocols such as RS-232, parallel, small computer system interface, anduniversal serial bus, etc. The memory 128 can be RAM, ROM, EPROM, andthe like. The controller 126 may be configured to provide control logicthat provides output instructions. In this respect, the controller 126may encompass a microprocessor, a micro-controller, an applicationspecific integrated circuit, and the like. The controller 126 may beinterfaced with an additional memory 132 that is configured to providestorage of computer software that provides the best-fit algorithm andthat may be executed by the controller 126. Such memory 132 may also beconfigured to provide a temporary storage area for data received by thecentral processor 124 from the machine vision controller 118.

Using the predefined best-fit algorithm, the function of the centralprocessor 124 is to calculate an actual as built vehicle body Areference feature of some type, such as an actual vehicle body Acenterline or gridline, or an actual vehicle Cartesian coordinate map orwireframe, and the like. The best-fit algorithm determines an imprecisedistance between as built features and design-intent locations anddivides such distance in half to establish the new gridlines orcenterlines for the actual body-in-white A in the as built conditionthereby reducing the error of the location of such feature by one-halffrom its design-intent-location. In the previous embodiment, such“calculation” was carried out by mechanical floating input sockets 40and a mechanical lever and crank mechanism 80. One example of thebest-fit algorithm can be better understood with reference to FIGS. 15and 16, which illustrate conceptual representations of the vehicle bodyA A.

FIG. 15 illustrates a conceptual view of the top of the vehicle body Awherein a design-intent locating feature B_(L) represents a point,surface, or the like on a left side of the vehicle body A A anddesign-intent locating feature B_(R) represents a point, surface, or thelike on the right side of the vehicle body A. The features B_(L), B_(R)are preferably located symmetrically cross-car Y and may consist ofhinge mounting points on A-pillars, leading edges of doors that arealready mounted to the vehicle body A, and the like. Actual locatingfeatures B′_(L) and B′_(R) are misaligned or displaced from thedesign-intent locating features B_(L) and B_(R) (as shown inexaggeration for clarity) due to tolerable dimensional variances of theactual vehicle body A from a theoretical design-intent vehicle body A,such as those variances induced by framing and welding stations upstreamfrom the workstation 110.

Datum D_(x) is a centerline created through design-intent locatingfeatures B_(L) and B_(R). Similarly, datum O_(y) is a centerline throughdesign-intent locating feature B_(L) that is parallel to the theoreticalcenterline D_(y) of the theoretical design-intent vehicle body A. Theterms datum, centerline, and net reference feature are used hereininterchangeably because all commonly relate to things from which othercoordinates are referenced. Moreover, the term centerline is equivalentto the terminology median feature, median point, or median surface. Inany case, datums D_(x) and O_(y) intersect to define a theoreticalCartesian origin from which the locations of the actual locatingfeatures B′_(L), B′_(R) can be referenced. The actual locating featuresB′_(L) and B′_(R) each have X and Y Cartesian coordinates components,wherein actual locating feature B′_(L) includes components X_(L) andY_(L), while actual locating feature B′_(R) includes components X_(R)and Y_(R). Thus, the amount of error due to processing events can bemeasured and the locations of the actual locating features B′_(L) andB′_(R), can be determined by mathematical reference to the datums D_(x)and O_(y). Similarly, the location of a cross-car centerline N₁ of theactual as built vehicle body A can be calculated by averaging the Ycomponents of the actual as built locating features B′_(L) and B′_(R).Expressed as an equation, this calculation amounts to (Y_(L)+Y_(R))/2.Expressed as a concept, the calculation amounts to balancing out thelocational errors of two features, between the features, to create abest fit condition regardless of previous built-in vehicle body Aerrors. Also, location of a fore-aft centerline N₂ of the actual asbuilt vehicle body A can be calculated by averaging the X components ofthe actual locating features B′_(L) and B′_(R). Expressed as anequation, this calculation amounts to (X_(L)+X_(R))/2. It iscontemplated that the present invention could use multiples of specificactual locating features B′_(L), B′_(R), C′_(L), C′_(R), along each sideof the vehicle body A to provide even higher accuracy for developing thenet reference features such as centerlines and the like for theattachment of components to the as built body-in-white A after framingand welding operations are completed.

Like FIG. 15, FIG. 16 represents a conceptual view of the vehicle bodyA, but from the front of the vehicle body A A looking rearward.Design-intent locating feature C_(L) represents a point, surface, or thelike on a right side of the vehicle body A, and design-intent locatingfeature C_(R) represents a point, surface, or the like on the left sideof the vehicle body A as viewed. The design-intent locating featuresC_(L), C_(R) are preferably located symmetrically opposed and may bepoints or surfaces on a motor compartment cross-member, a radiator rail,or the like. Actual locating features C′_(L) and C′_(R) are misalignedor displaced as a result of processing from the design-intent locatingfeatures C_(L) and C_(R) due to tolerable dimensional variances of theactual vehicle body A, such as those variances induced by upstreamframing and welding stations.

Datum D_(z) is a centerline created through design-intent locatingfeatures C_(L) and C_(R). Datum D_(z) defines a theoreticalone-dimensional origin from which the locations of actual locatingfeatures C′_(L) and C′_(R) can be determined. The actual locatingfeatures C′_(L) and C′_(R) each have Z Cartesian components. Actuallocating feature C′_(L) includes component Z_(L), while actual locatingfeature C′_(R) includes component Z_(R). Thus, the locations of theactual locating features C′_(L) and C′_(R), can be calculated bydimensional reference back to datum D_(z). Similarly, the location of atheoretical up/down net locating line or centerline N₃ of the actualvehicle body A A can be calculated by averaging the Z components of theactual locating features C′_(L) and C′_(R). Expressed as an equation,this calculation amounts to (Z_(L)+Z_(R))/2. Expressed as a concept, thecalculation amounts to balancing out any locational error between twolocating feature points in the Z coordinate direction to create abest-fit condition regardless of previous built-in vehicle body A errorsand regardless of the design-intent locations.

It is contemplated that the present invention may include other morecomplex methods of establishing the locations of the target locatingsurfaces B′_(L) and B′_(R) and the adjusted net reference features orcenterlines N₁, N₂, and N₃ that they establish. For example, the centralprocessor 124 may store a predefined design-intent wireframe data modelthat has millions of X, Y, and Z Cartesian coordinate data points thatrepresent the surface contours of a design-intent vehicle body A. Thedesign-intent wireframe data model may also include reference datums,from which the locations of actual locating features can be referencedon a coordinate-by-coordinate basis. The wireframe data model can beoffset from its design-intent condition, to a wireframe representationof the actual vehicle body A as sensed by the position sensingapparatuses. In other words, the position sensing apparatuses canestablish a relatively small amount of actual vehicle body Acoordinates, which can be established as datum points relative to thedesign-intent wireframe data model so as to replace corresponding datapoints in the design-intent wireframe data model. Then, the controller126 can run a program to adjust, or pull, all of the remainingdesign-intent or design-intent grid data points into correspondence withthe actual data points to reestablish a new as built grid system foreach entire vehicle body A after it is processed past theframing/welding station. In other words, the few actual vehicle body Acoordinates can be extrapolated in reference to the wireframe data modelreference datums to generate actual wireframe data of the actual vehiclebody A coordinates. From the actual wireframe data, vehicle body Acenterlines, or any other types of reference features, can be generated.

Referring again to the block diagram of FIG. 14, a robot controller 134receives the output instructions from the central processor 124 andthereby renders movement instructions to robots 136, such as NACHISC300F robots. The present invention adjusts the robots 136 with respectto newly established net best fit reference features or centerlines N₁,N₂, and N₃ created by averaging out the distances between actual asbuilt locating features. The net effect of such averaging results inreducing overall dimensional deviation from design-intent by one-half,as well as to establish an actual net location of the as-built vehiclebody A, and use the newly established net locating centerlines N₁, N₂,and N₃ from which to adjust positions of the robots 136 and associatedtooling components so that new net target attachment points can be moreeasily and accurately provided on the vehicle body A A to enable theattachment of components thereto without the need for oversizedattachment holes and slip planes. The robots 136 use the new netlocating centerlines N₁, N₂, and N₃ to locate relative thereto andperform work at new, adjusted target work locations. Under atheoretically perfect design-intent condition, the robots 136 wouldreference the design-intent centerlines or datums D_(x), D_(y), D_(z),O_(y) of the vehicle body A and move predefined distances therefrom totarget coordinates proximate the work to be performed on the vehiclebody A. Instead, however, the robots 136 reference the adjusted oractual as built centerlines or net locating lines N₁, N₂, and N₃ andthen move the predefined distances therefrom to target coordinates orpositions to create attachment points, holes or pads where outer bodycomponents can be associated to, without the need of any labor to makefinal fit adjustments to the panel.

Referring again to FIG. 13, the robots 136 each preferably includeend-effectors or tooling 138 of some kind, such as form and piercetooling, or form and clinch tooling exemplified by currently pendingU.S. patent application Ser. Nos. 10/641,580 filed Aug. 15, 2003 and10/329,893 filed Dec. 26, 2002 which are assigned to the assignee hereofand are all incorporated by reference herein. The present invention,however, is not limited to use with the above-described tooling 138 andmay include any devices including, but not limited to, gauges, measuringdevices, welders, lasers, sprayers, and the like. In accordance with thepreferred embodiment, the robot tooling 138 creates attachment featuresfor various vehicle outer body panels, sub-assemblies, and othercomponents that are to be attached to the vehicle body A in a downstreamstation from the framing/welding station.

As a result of balancing out the created processing or inherentdimensional errors of the vehicle body A, all attachment featurescreated by the robot tooling 138 are net located with respect to thenewly established net reference centerlines N₁, N₂, and N₃ (or othertypes of X, Y, and Z net reference features). Furthermore, the presentinvention essentially creates a best fit attachment feature andcompletely eliminates the need to provide for a slip plane in order toattach a component to the vehicle body A A. Therefore any outer bodycomponent, i.e. hood, fender, doors, decklid, liftgate, front bumper,rear or front facia, tail-lights, etc. being attached to thebody-in-white A can be fabricated with an attachment feature at net ordesign-intent locations since they will be attached to a best fit ornet-formed, attachment feature on the vehicle body A.

A method of the present invention is provided for assembling objects toa vehicle body A. The first step involves moving the vehicle body A,having target or actual locating features B′_(L), B′_(R), C′_(L), C′_(R)thereon, into an approximate location. The approximate location ispreferably established by the hard point locator pins 114 of theworkstation 110 that engages the preformed setup locating features ofthe vehicle body A and these locations are read into a microprocessor orcentral processor.

Thereafter, the actual as built locating features B′_(L), B′_(R),C′_(L), C′_(R) are engaged with the position detecting apparatuses 116and the position detecting apparatuses 116 are immobilized or the actuallocation of these features are read into a microprocessor 124. The termengaging is broadly defined to include interacting or operating upon,and the position detecting devices 116 are immobilized by the stanchions122 and overhead frame 120.

The third step involves determining an imprecise distance between theactual locating features B′_(L), B′_(R), C′_(L), C′_(R) of the vehiclebody A in one or more of X, Y and Z directions of a Cartesian coordinatesystem. In other words, the method establishes the actual location oflongitudinal and lateral locating features on the vehicle body A toestablish an actual coordinate system for the as-built vehicle body.

The fourth step involves creating a median of the imprecise distance, todefine net reference features N₁, N₂, N₃ at the median. In other words,the method of the present invention balances out or averages thelocations of the actual locating features B′_(L), B′_(R), C′_(L), C_(R)to establish actual vehicle body A centerlines, or other net as builtreference features.

The fifth step involves locating robot tooling 138 with respect to thenet reference features N₁, N₂, N₃ adjacent the vehicle body A. In otherwords, the method of the present invention adjusts the location ofcertain attachment point tooling from a nominal tooling location to are-configured target tooling location that is based on the as builtactual centerlines or as built net reference features.

The sixth step involves performing work on the vehicle body A toestablish a net attachment feature on the vehicle body A for assemblingan object at the net attachment feature location. In other words, themethod of the present invention effectively reforms a body surface tocreate an attachment feature to a design-intent location for such anattachment feature. Thus all attachment points are net-formed todesign-intent.

The method of the present invention may be performed as a computerprogram and the various Cartesian coordinate data may be stored inmemory 128 as a look-up table, wireframe model, or the like. Thecomputer program may exist in a variety of forms both active andinactive. For example, the computer program can exist as softwareprogram(s) comprised of program instructions in source code, objectcode, executable code or other formats; firmware program(s); or hardwaredescription language (HDL) files. Any of the above can be embodied on acomputer readable medium, which include storage devices and signals, incompressed or uncompressed form. Exemplary computer readable storagedevices include conventional computer system RAM (random access memory),ROM (read only memory), EPROM (erasable, programmable ROM), EEPROM(electrically erasable, programmable ROM), and magnetic or optical disksor tapes. Exemplary computer readable signals, whether modulated using acarrier or not, are signals that a computer system hosting or runningthe computer program can be configured to access, including signalsdownloaded through the Internet or other networks. Concrete examples ofthe foregoing include distribution of the graphics display classes,their extensions, or document-producing programs on a CD ROM or viaInternet download. In a sense, the Internet itself, as an abstractentity, is a computer readable medium. The same is true of computernetworks in general. It is therefore to be understood that the method ofthe present invention may be performed by any electronic device capableof executing the above-described functions.

This embodiment of the present invention is an improvement over priorart techniques of assembling components to a body. Many prior arttechniques involve developing correction data at each individualassembling position for individual components to be attached to a body.In other words, prior art techniques require calculating the mountinglocations for a vehicle body A on a component-by-component basis, suchthat the mounting of each component must be separately, individuallyadjusted. Such a process is time-consuming, complex, and ultimately notas desirable as the present invention since such prior art techniquesstill usually require the use of slip-planes to adjust the mounting ofbody components.

Instead the present invention provides apparatus and techniques forbalancing out misalignment of component attachment features betweenposition detecting apparatuses to generate new centerlines or netreference features of the vehicle at half the distance of overalldeviation of the individual component attachment features. This avoidsthe inferior prior art process of individually recalculating theassembling positions for each body member to be attached to a vehiclebody A at a specific location. Accordingly, the present invention ismore accurate as effectively compared to the prior art, because thepresent invention uses a best-fit algorithm to net-form attachmentfeatures of the total vehicle at design-intent coordinates, regardlessof misalignments due to processing through the framing/welding stationof the vehicle body A. As is clear to a person skilled in the prior artthe concept can easily be adapted to a specific intent application suchas fitting a pivotable window into a window opening in the vehicle bodyto accomplish a best fit assembly position of the hinges for the window.

The invention including the method and apparatus as heretofore set forthmay be embodied in other specific forms without departing from thespirit or essence of the invention. The presently disclosed embodimentsare, therefore, to be considered in all respects as illustrative and notas a restriction on the invention, the scope of the invention beingindicated by the appended claims. Rather the foregoing description andall changes that come within the meaning and range of equivalency of theclaims are to be embraced therein.

1. An apparatus for creating net attachment features on athree-dimensional object defined by X, Y and Z Cartesian coordinates,said apparatus comprising: a three-dimensional body having one end andan opposite end, each end of said three-dimensional body having at leastone primary locating point thereon, said at least one primary locatingpoint selectively located within a known tolerance range with respect tosaid X, Y and Z directions of said Cartesian coordinate system; meansfor storing design-intent locations of said at least one primarylocating point on said three-dimensional body defined by X, Y and ZCartesian coordinates; means for establishing an actual location of saidat least one primary locating point on said three-dimensional body, ineach of said X, Y and Z directions, said actual location being definedas a datum position; programmable means for comparing said actuallocation of said at least one primary locating point on saidthree-dimensional body with said design-intent location of said at leastone primary locating point in said means for storing in each of said X,Y and Z directions, said comparing means further comprising:microprocessor means for determining an imprecise distance in each ofsaid X, Y and Z directions between said actual location of said at leastone primary locating point with said design-intent location; and meansfor creating a median point of said imprecise distance in each of saidX, Y and Z directions, said median point of said imprecise distance ofsaid at least one primary locating point of said three-dimensional bodybeing an adjusted net position of said at least one primary locatingpoint in each of said X, Y and Z directions on said three-dimensionalbody; and programmable means for directing at least one programmablework performing device to said adjusted net position to locate thereatwhereby said work performing device performs work on saidthree-dimensional body such that at least one adjusted net attachmentlocation is established for objects to be attached to saidthree-dimensional body.
 2. The apparatus claimed in claim 1, whereinsaid three-dimensional body comprises a welded body-in-white.
 3. Theapparatus as claimed in claim 1, wherein said means for establishing anactual location of said at least one primary locating point on saidthree-dimensional body further comprises at least one triangulation-typesensor illuminator means for generating image data usable by a machinevision controller to determine three-dimensional measurements of anobject.
 4. The apparatus as claimed in claim 1, wherein said means forstoring design-intent locations of said at least one primary locatingpoint on said three-dimensional body comprises a microprocessor.
 5. Theapparatus as claimed in claim 1, wherein said means for comparing saidactual location of said at least one primary locating point on saidthree-dimensional body with said design intent location stored in saidmicroprocessor is a central processor means, said central processormeans determining said imprecise distance in each said X, Y and Zdirections between said actual location of said at least one primarylocating point and said design-intent location.
 6. The apparatus asclaimed in claim 5, wherein said central processor further calculatessaid median point of said imprecise distance in each said X, Y and Zdirections in order to establish a best-fit centerline or grid line oran actual vehicle Cartesian coordinate map or wire frame for thebody-in-white in an as built condition whereby any error between an asbuilt location of said at least one primary locating point and saiddesign-intent location of said at least one primary locating point isreduced by one-half.
 7. The apparatus as claimed in claim 1, whereinsaid means for directing said at least one programmable work-performingdevice is a robot means.
 8. The apparatus as claimed in claim 7, whereinsaid robot means further comprises at least one robot located alongsidesaid three-dimensional body; and a work-performing tool attached to saidrobot.
 9. A master locating apparatus for establishing a plurality ofnet attachment features on an imprecisely constructed three-dimensionalbody structure of unknown dimensional accuracy within a known tolerancerange, relative to an X, Y and Z Cartesian coordinate system, saidimprecisely constructed three-dimensional body structure adapted forattachment of one or more external members, said apparatus comprising:at least one columnar member located adjacent said three-dimensionalbody; at least two programmable position detecting apparatuses attachedto said at least one columnar member, said at least two programmableposition detecting apparatuses further being located in spaced apartrelation on opposing sides of said three-dimensional body structure,each of said at least two programmable position detecting apparatusesfurther comprising: programmable means for visually engaging saidthree-dimensional body structure at least one predetermined primarylocating point to establish an actual location in at leasttwo-dimensional planes of said three-dimensional body structure, saidprogrammable means for visual engaging said three-dimensional bodystructure located alongside said three-dimensional body structure; meansfor storing design-intent locations of selective primary locating pointson said three-dimensional body structure defined by X, Y and Z Cartesiancoordinates; microprocessor means for comparing said actual location ofsaid at least one predetermined primary locating point in said at leasttwo-dimensional planes with said design-intent locations of said atleast one predetermined primary locating point in each of said at leasttwo-dimensional planes to establish an imprecise distance in each ofsaid two-dimensional planes between said actual location and saiddesign-intent location in each said two-dimensional planes; means forcreating a median point of said imprecise distance between said actuallocation found by said programmable visual engaging means for each ofsaid two-dimensional planes and said design-intent location, said medianpoint of said imprecise distance in each of said two-dimensional planesdefining an adjusted net location; and means for communicating saidadjusted net location to a work performing device whereby said workperforming device performs work on said three-dimensional body structurewith respect to said adjusted net location.
 10. The apparatus claimed inclaim 9, wherein said at least one columnar member comprises a front andrear gantry straddling a production line such that saidthree-dimensional body structure can pass through thereunder.
 11. Theapparatus claimed in claim 10, wherein each of said at least twoprogrammable position detecting apparatuses each have a laser thereon.12. The apparatus claimed in claim 11, wherein said means for creating amedian point of said imprecise distance comprises a microprocessor. 13.The apparatus claimed in claim 10, wherein said at least twoprogrammable position detecting apparatuses comprise a first pair ofprogrammable position detecting apparatuses disposed on opposite sidesof said three-dimensional body structure, and a second pair ofprogrammable position detecting apparatuses disposed on opposite sidesof said three-dimensional body structure, each of said first and secondpair of position detecting apparatuses having a laser sensor thereon.14. The apparatus claimed in claim 9, wherein said at least twoprogrammable position detecting apparatuses comprise a first pair ofposition detecting apparatuses disposed on opposite sides of saidthree-dimensional body structure, and a second pair of positiondetecting apparatuses disposed on said opposite sides of saidthree-dimensional body structure, each of said second pair of positiondetecting apparatuses having a laser mounted thereto.
 15. The apparatusas claimed in claim 9, wherein said programmable means for visuallyengaging said three-dimensional body structure at an actual location ofsaid at least one primary locating point in at least two-dimensionalplanes on said three-dimensional body further comprises at least onetriangulation-type sensor illuminator means for generating image datauseable by a machine vision controller to determine three-dimensionalmeasurements of an object.
 16. The apparatus as claimed in claim 9,wherein said means for storing design-intent locations of said selectiveprimary locating points on said three-dimensional body comprises amicroprocessor.
 17. The apparatus as claimed in claim 9, furthercomprising means for comparing said actual location of said at least oneprimary locating point on said three-dimensional body with saiddesign-intent location stored in said microprocessor is a centralprocessor means, said central processor means determining an imprecisedistance in each X, Y, and Z directions between said actual location ofsaid at least one primary locating point and said design-intentlocation.
 18. The apparatus as claimed in claim 17, wherein said centralprocessor further calculates a median point of said imprecise distancein each said X, Y and Z directions in order to establish a best-fitcenterline or grid line or an actual vehicle Cartesian coordinate map orwire frame for a body-in-white in the as built condition whereby anyerror between an as built location of said at least one primary locatingpoint and said design-intent location of said at least one primarylocating point is reduced by one-half.
 19. The apparatus as claimed inclaim 9, wherein said means for communicating said adjusted net locationto a work performing device further comprises; robot means located inspaced relation to said three-dimensional body structure, said robotmeans having a work-performing device attached thereto.
 20. Theapparatus as claimed in claim 19, wherein said robot means furthercomprises at least one robot located alongside said opposing sides ofsaid three-dimensional body; and a work-performing tool attached to eachof said robots.
 21. A method for assembling objects to athree-dimensional body, said method comprising the steps of: moving saidthree-dimensional body having one end and an opposite end into a fixturelocation, said three-dimensional body having at least one primarylocating point thereon, visually engaging said at least one primarylocating point of one end of said three-dimensional body with at leastone programmable position detecting apparatus reading an actual locationof said at least one primary locating point, said actual location beingdefined by X, Y and Z Cartesian coordinates; storing design-intentlocations of selective primary locating points on said three-dimensionalbody defined by X, Y and Z Cartesian coordinates into a microprocessor;determining an imprecise distance by calculating in said microprocessorthe variance between said design-intent location and said actuallocation of said at least one primary location point of said one end ofsaid three-dimensional body in each one of X, Y and Z directions of theCartesian coordinate system; creating a median point of said imprecisedistance, said median point defining a new adjusted net position at saidmedian point of said imprecise distance; locating at least one workperforming device with respect to said new adjusted net positionadjacent said three-dimensional body; and performing work on saidthree-dimensional body to establish a net attachment feature on saidthree-dimensional body for assembling at least one object at said netattachment feature of said three-dimensional body.
 22. The methodaccording to claim 21 further comprising the step of assembling andwelding said three-dimensional body prior to said step of visuallyengaging said at least one primary locating point such that minimaladditional variation is introduced after the position of said at leastone primary locating point is established.
 23. The method according toclaim 21, wherein the step of visually engaging said at least oneprimary locating point comprises the step of providing said at least oneprogrammable position detecting apparatus with a laser sensor, wherebysaid laser sensor visually engages said at least one primary locatingpoint to establish two of said X, Y, and Z directions, and wherein saidstep of visually engaging said at least one primary locating pointcomprises the step of providing another, at least one position, primarydetecting apparatus with a second laser sensor and the second of saidlaser sensors visually engages said at least one primary locating pointto establish the third of said X, Y and Z directions.
 24. The methodaccording to claim 23, wherein the step of visually engaging said atleast one primary locating point of one end of said three-dimensionalbody with said at least one programmable position detecting apparatuscomprises the step of visually engaging a first pair of primary locatingpoints on said one end of said three-dimensional body with a first pairof programmable position detecting apparatuses disposed on oppositesides of said three-dimensional body; and visually engaging a secondpair of primary locating points on said opposite end of saidthree-dimensional body, said second pair of programmable positiondetecting apparatuses disposed on said opposite sides of saidthree-dimensional body.
 25. The method according to claim 23, whereinthe step of creating a median point of said imprecise distance comprisesthe step of providing a microprocessor to receive data from said step ofvisually engaging said at least one primary locating point on each endof said three-dimensional body and comparing said data with saiddesign-intent positions stored in said microprocessor to generate saidmedian point of said imprecise distance.
 26. The method according toclaim 23, wherein the step of locating at least one work performingdevice with respect to said new adjusted net position further comprisesthe step of communicating a calculated position of said median point tosaid work performing device.
 27. A master locating apparatus mountedalongside of the direction of travel of an assembly line for athree-dimensional body structure of unknown dimensional constructionwithin a known tolerance range, said master locating apparatuscomprising: at least two columnar members in spaced apart relationshipon opposite sides of said assembly line; a support member havingrespective ends, one of said ends attached to one of said at least twocolumnar members, the other of said ends attached to the other of saidat least two columnar members; at least two programmable positiondetecting apparatuses located in spaced apart relations on oppositesides of said assembly line to permit said assembly line to passtherebetween, each of said at least two programmable position detectingapparatuses further having: means for visually engaging opposite sidesof said three-dimensional body structure at a plurality of preselecteddefined locations to establish an actual position in at leastthree-dimensional planes of said plurality of preselected definedlocations of said three-dimensional body structure on each side of saidthree-dimensional body structure when said three-dimensional bodystructure is between said visually engagement means, said means forvisually engaging located alongside said assembly line and visuallyengaging said three-dimensional body structure at said plurality ofpreselected defined locations; programmable means for storingdesign-intent locations of each of said plurality of preselected definedlocations of said three-dimensional body: programmable means fordetermining an imprecise distance between each of said plurality ofpreselected defined locations and the design-intent location of each ofsaid plurality of preselected defined locations of saidthree-dimensional body: means for establishing a median distance pointof said imprecise distance to establish an adjusted net position of eachof said plurality of preselected defined locations on said one side andsaid opposing side of said three-dimensional body structure of each ofsaid plurality of preselected defined locations of saidthree-dimensional planes, said median distance defining an adjusted netposition of each of said plurality of preselected defined locations ofsaid three-dimensional body structure; and means for performing work onsaid three-dimensional body structure with respect to said adjusted netposition.
 28. The apparatus claimed in claim 27, wherein said means forvisually engaging opposite sides of said three-dimensional bodystructure further comprises a front and rear gantry straddling aproduction line such that said three-dimensional body structure can passthrough thereunder.
 29. The apparatus claimed in claim 27 wherein saidmeans for visually engaging opposite sides of said three-dimensionalbody structure, said means further comprises a first plurality ofprogrammable position detecting apparatuses, at least two of said firstplurality of programmable position detecting apparatuses being disposedon opposing sides of said three-dimensional body structure.
 30. Theapparatus claimed in claim 29, wherein said means for establishing theactual location of said preselected defined locations on each end ofsaid three-dimensional body comprises a second plurality of programmableposition detecting apparatuses each having a laser sensor, at least twoof said second plurality of programmable position detecting apparatusesbeing disposed on opposing sides of said body.
 31. The apparatus claimedin claim 27, wherein each of said at least two programmable positiondetecting apparatuses include a laser.
 32. The apparatus claimed inclaim 27, wherein said means for establishing a median distance point ofsaid imprecise distance further comprises a microprocessor.
 33. Theapparatus claimed in claim 27, wherein said three-dimensional bodystructure comprises a welded body-in-white.
 34. The apparatus claimed inclaim 27, wherein said at least two columnar members comprise a frontand rear gantry straddling a production line such that saidthree-dimensional body structure can pass through thereunder.
 35. Theapparatus as claimed in claim 27, wherein said means for visuallyengaging opposite sides of said three-dimensional body structure at aplurality of preselected defined locations to establish a datum positionin at least three-dimensional planes of said three-dimensional bodystructure further comprises at least two triangulation-type sensorilluminator means for generating image data usable by a machine visioncontroller to determine three-dimensional measurements of an object. 36.The apparatus as claimed in claim 27, wherein said programmable meansfor storing design-intent locations of each of said plurality ofpreselected defined locations of said three-dimensional body comprises amicroprocessor.
 37. The apparatus as claimed in claim 27, wherein saidmeans for establishing a median distance further comprises programmablemeans for comparing said actual location of each of plurality ofpreselected defined locations on said body with said design intentlocation stored in said programmable means for storing, saidprogrammable means for comparing determining an imprecise distance ineach said X, Y and Z directions between said actual location of each ofsaid plurality of preselected defined locations and said design-intentlocation.
 38. The apparatus as claimed in claim 37, wherein saidprogrammable means for comparing further calculates a median point ofsaid distance in each X, Y and Z directions in order to establish abest-fit centerline or grid line or an actual vehicle Cartesiancoordinate map or wire frame for the body-in-white in an as builtcondition whereby any error between an as built location of each of saidpreselected defined location and said design-intent locations of each ofsaid preselected defined locations is reduced by one-half.
 39. Theapparatus as claimed in claim 27, wherein said means for performing workfurther comprises a robot means.
 40. The apparatus as claimed in claim39, wherein said robot means further comprises at least one robotlocated alongside each of said two columnar members on opposite sides ofsaid assembly line, and a work performing tool attached to said at leastone robot.
 41. An apparatus for creating net attachment features on athree-dimensional object defined by X, Y and Z Cartesian coordinates,said apparatus comprising: a three-dimensional body having at least oneprimary locating feature thereon; means for storing design-intentlocations of said at least one primary locating feature of saidthree-dimensional body: means for establishing an actual location ofsaid at least one primary locating feature in each of said X, Y and ZCartesian coordinates; means for calculating an imprecise distancebetween said actual location of said at least one primary locatingfeature with said design-intent location of said at least one primarylocating feature in each of said X, Y and Z Cartesian coordinates; meansfor creating a median of said imprecise distance in each of said X, Yand Z Cartesian coordinates, said median of said imprecise distancedefining an adjusted net reference feature; and means for locating atleast one work performing device with respect to said adjusted netreference feature, whereby work performed on said three-dimensional bodyestablishes at least one adjusted net attachment feature location forobjects to be attached to said three-dimensional body.
 42. The apparatusas claimed in claim 41, further comprising means for net-formingsurfaces of said three-dimensional body at design-intent coordinates forsaid objects.
 43. A method for assembling objects to a three-dimensionalbody comprising the steps of: moving said three-dimensional body havingas-build defined locating features thereon into a fixture location;engaging said locating features with programmable position detectingapparatuses; storing design-intent positions of said defined locatingfeatures of said three-dimensional body in a central processor;determining an imprecise distance between said as-build defined locatingfeatures of said three-dimensional body and said design-intent positionsof said defined locating features in one or more of X, Y and Zdirections of a Cartesian coordinate system; creating a median of saidimprecise distance in each of said X, Y and Z directions to definebest-fit net reference features; and locating robot tooling with respectto said best-fit net reference features to perform work on saidthree-dimensional body.
 44. The method as claimed in claim 43, furthercomprising the step of providing a programmable robot with a workperforming tool attached thereto to net-form at least one attachmentfeature on said three-dimensional body for assembling said object tosaid at least one net attachment feature.